1. Field of the Invention
This invention relates to a magnetic head of a construction, in which a plurality of head elements are exposed to outside through an opening formed in a shield case.
2. Description of the Prior Art
The magnetic head of the above-described construction has heretofore been realized as shown in FIGS. 1A and 1B of the accompanying drawing, wherein a magnetic core half 2, around which a winding 3 is wound and which has a magnetic gap 4 formed in its top part, is housed in a shield case 1 made of a magnetic material, and the top of the magnetic core 2 is positioned at a window opening 1a formed in the shield case 1 so as to enable it to contact a magnetic recording medium 6 slide-moving thereon in the direction of an arrow A for magnetic recording and reproduction of informations to and from the recording medium 6. In this known construction, a plurality of magnetic cores 2, 2' are provided for effecting the recording and reproduction on a plurality of tracks of the magnetic recording medium, thus constituting a multi-element structure.
In such multi-element magnetic head accommodated in the shield case of magnetic material, however, there inevitably occurs a phenomenon such that signals reproduced by one head element transfer to other head element due to leakage of magnetic flux when those signals recorded in the magnetic recording medium 6 are to be reproduced. Such phenomenon will hereinafter be referred to as "cross-talk". This cross-talk is expressed in terms of a ratio of a reproduction output of the head element at a non-recorded zone of the running magnetic recording medium to a reproduction output of the head element at a recorded zone of the recording medium. It has been possible that, up to 40 to 50 dB or so of this ratio, the cross-talk can be avoided by interposing between the head elements 2, 2' a shut-off plate 5 of a magnetic material functioning to prevent the leakage magnetic flux from moving from one head element to the other. However, when the ratio is above 50 dB, in particular 60 dB and above, the shut-off plate will no longer serve any purpose, i.e., when both edge portions a, a' or either of them in the window 1 a of the above-mentioned shield case 1, which are substantially perpendicular to the travelling direction of the recording medium 6, touches the recording medium at the time of reproduction, a very small magnetic flux which the magnetic recording medium picks up at a location between the edge portions a, a' and the magnetic gaps 4, 4' greatly affect the result of reproduction.